The present invention relates to an apparatus for reducing a treadling force necessary for working a pedal, such as a clutch pedal of an automobile, and more specifically to an improvement of means for urging the pedal.
In conventional pedal-load lightening apparatuses, a torsion coil spring is used as means for urging a pedal. One such apparatus is disclosed in Japanese Utility Model Disclosure No. 58-6629.
In this prior art apparatus, a support shaft is attached to a support bracket, which is fixed to a car body. A pedal arm is rockably supported on the shaft. It has a lever which rocks in one therewith. A torsion coil spring, having first and second ends, is disposed between the free end of the lever and the support bracket. The first end of the spring is rotatably supported on the bracket, while the second end is anchored to the lever.
When the pedal arm is forced in by treadling, the second end of the torsion coil spring moves in the treadling direction from its initial position. Before the second end reaches a critical position at a predetermined rotational angle to the initial position, therefore, the repulsive force of the spring urges the pedal arm to return. When the arm rocks to the critical position, the repulsive force of the coil starts urging the arm to move in the treadling direction. Thus, the necessary treadling force on the pedal can be reduced.
In the prior art apparatus described above, if a torsion coil spring with a larger spring constant or a longer lever is used to increase reduction of the necessary treadling force, the repulsive force of the spring increases, and a greater treadling force is needed in the initial stage of pedaling operation. Thus, the pedal cannot be easily worked at the start.